Melee Academy: Unarmed vs. Knife – Technical Disarms

Thursday is GURPS Day, and what better way to spend it than with another cross-blog installment of Melee Academy. Spawned by a thread oddly enough called Unarmed vs. Knife on the SJG Forums, hopefully a lot of people will contribute their own thoughts.

Others will probably hit the GURPS RAW pretty well, and hopefully still more will be inspired to give their favorite tactics from other game systems.

Me? I’m getting Technical.

Other Blogs, Other options


I wrote this one pretty late. I’m sure I missed a few things, made some suboptimal choices, etc. Good thing you can either comment or choose to post your own – I’ll link to it! Here are the list of all the Melee Academy posts made by other bloggers . . .


The Combatants


The thread in question takes the right perspective – unarmed disarms vs a guy with a weapon are dangerous, and should only be resisted through a disarm if you have a skill advantage. The thread posits someone with Knife-12 (about a 75% chance to stab the torso) vs. a guy with some sort of unarmed skill at an impressive 18. However, since TG depends a lot of ST, let’s get picky with a shortish character description.

Mack Dagger [18 points]


Mack is a seasoned fighter, with some experience.

ST 11; DX 10; IQ 10; HT 10
Knife [DX+2]-12; Knife Parry-8*
Trained ST 11; Grip ST: 5
1H Control Point roll: 1d-4; 2H CP roll: 1d-1
*”Knives” – and that’s all of them in Basic, are -1 to Parry. So Skill-12 is Parry-8. This matters. I got it wrong in the original version (was tired), but this will change percentages a bit.

Marty Shallarts [72 points]

We’re going to vary him up a bit, but let’s start by assuming a build that should notionally be effective against weapons: someone with high Judo skill. We’ll look at other skills too. I won’t go overboard with his stats, but I will make him an experienced fighter with slightly high agility.

ST 12; DX 11; IQ 10; HT 10
Judo [DX+7]-18; Judo Parry-12
Trained ST 14; Training Bonus +2. Grip ST 6.
1H Control Point roll: 1d-3; 2H CP roll: 1d

Marty would have a higher Trained ST with Wrestling, at Trained ST 16, and 1H Trained ST 10, but he’d suffer the usual penalties to parry weapons, which Judo doesn’t have to worry about. The bonus for favoring Judo or Karate, though, can be found on p. B376:

Parrying Unarmed Attacks: If you successfully parry an unarmed attack (bite, punch, etc.) with a weapon, you may injure your attacker. Immediately roll against your skill with the weapon you used to parry. This roll is at -4 if your attacker used Judo or Karate. If you succeed, your parry struck theattacker’s limb squarely. He gets no defense roll against this! Roll damage normally.

The other contender is Karate. This gives the nice damage bonus, ability to parry weapons, and access to Kicking, which is darn nice – it allows equal reach vs. Reach 1 weapons, and against smaller knives that are Reach C, you actually have a reach advantage.

My original calculation suggested that if your foe successfully parried your unarmed grapple, you simply got hit. That’s not right – he rolls flat skill (or at -4 vs. Judo or Karate) and if he succeeds, you’re hit. That -4 is a big, big deal with Judo/Karate. It means that 3/4 of the time, your parried grapples or strikes will have no ill effect on you. 

In our notional combat, we’ll put the combatants at two hexes distance to start, Marty will go first, having higher speed, but his first move will likely be to Wait until Mack steps into range at one yard distance.

Charming Disarming Methods


There are a few ways to take a weapon away within the rules for TG, and the one most like RAW comes first.

Knocking a Weapon Away


This technique is on p. B401 and on pp. 13-14 of Technical Grappling, but honestly TG mostly just repeats Basic here.

Grappling Skills: Judo


First, Marty has to attack Mack; this will trigger Marty’s Wait, and Marty will step and attack to knock Mack’s weapon away. If he’s using Judo, per the basic character above, he’ll roll at Judo, -2 since he’s not using a special weapon, and -5 for attacking a knife (a longer knife with Reach 1 might only be at -4). He is thus at about -7, for a fairly low Judo-11 to hit. Mack will parry, using the knife. 

He’s got Parry-8, and if he does parry, he’ll do damage to Marty 25% of the time. So Marty will just miss 37% of the time. He’ll hit and Mack will fail to parry 47% of the time. He’ll hit and be harmlessly parried about 12%, and hit and be injured 4% of the time. In all cases, the two fighters end in close combat.

If the judo attack is successful, It’s a quick contest of DX or ST-based weapon skills. Marty will win this easily, as it’s 19 vs. 13, ST-based for both. Just shy of 90% of the time, Marty will win and knock the weapon away (total odds here are about 36%), while another 7.5% of the time, Marty will tie or lose by less than 3, making the weapon Unready.

Net/net for Judo: 

  • Successful Instant Disarm: 42%
  • Not Disarmed, Weapon Unready: 4%
  • Miss, or Hit but no disarm: 39%
  • Disarm Parried, no injury: 12%
  • Disarm Parried, take damage: 4%

Wrestling is a similar case, but with equal points Marty will be Wrestling-19 instead of 18 leaving him at Wrestling-12 instead of Judo-11. However, his odds of being cut on a parry are much higher – Mack will roll against Knife-12 to cut him on a parry. Skipping the math:

Net/net for Wrestling:

  • Knife Disarm: 51%
  • Knife Unready: 4%
  • Miss or No Result: 26%
  • Parried but not injured: 5%
  • Parried and injured: 14%

Karate

Now, with Karate the basic numbers are slightly worse than Judo, because instead of attacking by stepping into CC, you will kick first, and then step back. This gives you a disarm attempt, and keeps you out of range unless your foe does a Committed or All-Out Attack (not good for him), or expends fatigue. On the flip side, your net skill is Karate-9 instead of Judo-11, unless you spend the three points to buy off kicking to flat skill. At equal points, for the express purpose of disarm, it’s probably best to use Karate-17, Kicking-17 and a point left over for something.

Assuming you take that trade, and you’re at Karate-10 for the initial attack, and rolling ST-based Karate/Kicking-18 vs. ST-based Knife-13 for a Quick Contest to disarm, the final probabilities are:

Net/net for Karate

  • Knife Disarm: 32%
  • Knife Unready: 4%
  • Miss or No Result: 51%
  • Parried but not injured: 9%
  • Parried and injured: 3%
Worse than wrestling by the numbers, but remember that this exchange leaves the karateka with the same two-yard distance as the starting point, truly leveraging the reach of the kick. the odds of anything bad happening here are very low, though it’ll take a couple of turns to succeed. From Mack’s perspective, he may want to consider things like Aggressive Parry on the disarm attempt, but his skill is low enough that might not be a good option. Ironically, All-Out Defense (Parry) might be a good idea for Mack, stepping into Marty’s Wait. Likewise with Defensive Attacks.

Brawling

Ah, brawling! An Easy skill and you can buy off the kicking penalty. That gives Brawling-19/Kicking-19 and a point left over for a Perk. So as good as Judo in outcomes and you can play the run-away game. On the flip side, if you’re parried, you’re in the same boat as Wrestling – you’ll be injured 75% of the time.

Net/net for Brawling

  • Knife Disarm: 53%
  • Knife Unready: 3%
  • Miss or No Result: 26%
  • Parried but not injured: 5%
  • Parried and injured: 14%

Overall, when using Knocking a Weapon Away, what skills you want depends on your goals. If the goal is don’t get injured, Karate and Judo are the winners, with Judo a bit more likely to actually disarm the guy, but you wind up in close combat very fast. For the goal of highest percentage of a disarm, you want Brawling, then Wrestling, then Judo, then Karate.

Also, it’s possible – perhaps even likely – for Mack to use a retreating parry to defend against knocking a weapon away. This will increase the likelihood of Marty getting injured, but leave Mack back at his original starting place. Not a bad move:

Mack retreats vs. Judo-11 Disarm

  • Knife Disarm: 35%
  • Knife Unready: 3%
  • Miss or No Result: 38%
  • Parried but not injured: 18%
  • Parried and injured: 6%

You can see that the chance of Mack injuring Marty is still small, but 50% larger than it was. Furthermore, the retreat option has lowered Marty’s victory conditions by a bit.

Bit of a coin toss, but then, it’s a coin toss at Knife-12 vs Judo-18. So it’s a risky thing even with a high level of skill mismatch! Interestingly, playing with the numbers a bit, the actual disarm attempt is fairly benign. You have to really be close to similar skill – even with penalties – before the (low) odds of a successful disarm come close to the odds of getting knifed during the disarm. Of course, the odds of getting actually knifed after your Wait is expended on a move that five times in six results in “no effect” go up pretty fast with anything other than Judo or Karate, and pretty fast even with them.

Skilled Instant Disarms – Technical Grappling


While you can do this offensively, the grappling disarms (naturally requiring a grapple) probably come into their own responding off of a parry. Let’s start with that, then.

Mack steps in to attack; Marty does a Judo Parry – and he will elect to use Martial Arts’ slip option, maintaining Reach 1 but giving +2 to Parry. This results in Parry-14. He wants to grapple, so he elects Grabbing Parry, which is at -8 to Parry in a realistic game (-2 base, -3 to parry a thrust with Judo, -3 to get the arm/hand; more forgiving GMs will say ‘no penalty’ to parry with Judo). So even with a Slip, he’s at Parry-6, Yeeowch.

In retrospect, this piles on too many penalties. Perhaps consider Grabbing Parry to default to flat grappling Parry, but with the modifiers as written. That makes it -1 to parry unarmed and grab an arm, -2 for a hand; -3 to Judo Parry and grab a weapon, or -6 to bypass the weapon and capture the arm/hand holding it. The slip means you’re actually at a bonus of Parry+1 vs unarmed for an arm, but at -4 for a knife). Call this an optional rule. Stacking this with All-Out Defense (a good idea if you’re defending vs. a knife) helps tame the as-written penalties.

Using Grabbing Parry-8 (taking my own ‘modifiers too harsh advice above), Mack will thus actually stab Marty about 56% of the time, miss 25% of the time . . . but the remaining 19%, Marty will successfully grapple Mack, but roll 1d-4 CP. On the average, zero, but maybe up to 2. Trained ST does not help here.

On Marty’s turn, he may attempt the Instant Disarm. He rolls vs Arm Lock or Disarming (in this case based on Trained ST 14, per TG p. 36), at -5 for the foe’s grip on the weapon – a net Disarming-16. Mack rolls vs. Retain Weapon, which again is flat Knife skill here but using the average progression (13), but at an average -0.5 penalty for Marty’s grapple (we’ll treat that as no penalty), for Retain Weapon-13. Marty will come out on top of this contest about 72% of the time.

That still makes for bad odds: Mack hits marty 56% of the time, misses 25% of the time, 14% of the time Marty parries and disarms Mack, and 5% Marty parries but doesn’t disarm (but retains his grapple). More than 50% of the time, Marty gets cut. About one time in seven Marty can achieve an instant disarm on the parry. For the rest, it’s either a miss or a grapple, but no clean result. He’s four times as likely to get cut as to use a grapple-disarm successfully, but it will be his turn next, and he can follow up by developing the grapple further.

Multi-Turn Disarms


If you’re willing to be a tetch more patient, you can go for a grapple-and-disarm using an offensive grapple. Probably using the same wait maneuver above, when your foe steps into range, you also step and attack the foe’s arm at -2 or his hand at -4. Even though you’re grappling, moving past the weapon makes this like a strike.

Still, Marty has a lot of skill. So Judo-18 can target the arm at -2, for Judo 16. In this case, the key is to not get stabbed, so use Deceptive Attack to bring your skill down to 14, for -1 to his defenses. So 9% of the time, Marty misses. 15% he is parried, but only gets cut about 4% of the time with Judo. But the remainder, 77% of the time, he achieves a full-strength grapple on his foe’s arm, scoring 1d control points in the process. His foe is likely at -1 or -2 to ST and DX from this.

Note that +Peter V. Dell’Orto recommends DAing all the way down to 10, because the most important thing for you is to have his parry not succeed. Against skilled foes, this is definitely true, since your opponent gets a full-skill attack against you unless you’re attacking with Judo or Karate. With those skills, though, I’m not so sure.

Alternately, forgo the deceptive attack, and accept a -2 penalty to rotate into your foe’s side arc. That gives you a slightly lower chance of a successful grapple, but in the end you apply 1d CP, and then he’s at -2 to defend and attacks are wild swings (attacking into a Side hex) unless he turns to face you, and a 44 chance that he parries you with his knife.

Let’s say you do the second one. Mack gets his turn, having been alarmingly grappled. He’s in CC now (knife so no big deal), but at -2 to attack from the CP, and -5 to attack a foe in his side hex, for -7 to hit, leaving him with Knife-5. He can try and spin in place using Change Position based on DX at -1, but that forgoes his attack. So he’s either looking at about a 15% chance to stab you, or a highly unfavorable quick contest to spin in place. Even if he does stab you, you can use a hands-free counter to defend against it.

The next turn, the sensible thing is to apply Arm Lock, attacking at Judo-18, and perhaps even accepting -4 to achieve the rear arc. He’ll defend at -1 from the control points, and -2 due to an attack from the side. He can retreat, though. So Judo-14, defended vs Parry-6. 9% of the time nothing happens; 15% of the time he defends and will cut you 1/4 of the time; the remainder, 76% of the time, you apply another 1d control points to the arm, and the joint is locked, so he can no longer threaten you with the knife unless he breaks free (good luck with that). You’re in his rear arc, too.

You probably have at least 4 CP here, against his Grip ST of 5. The smart money here is to either take him to the ground (where the posture penalties make him basically helpless, especially combined with your raking his rear arc – he’s at -5 to defend against grappling attacks and can’t attack at all), then obtain a few CP more, then spend three (margin of victory capped at double CP expenditure) to apply pain to his grip (you may need to change grips to the hand). Since pain counts to reduce grip CP, he’ll first unready and then drop the knife.

Parting Shot


You can’t use striking skills to achieve multi-turn disarms, so they’re out. You can, however, still use full Judo Parry to defend against weapons – you just can’t secure a grapple while doing so. Wrestling is at -3 just to parry, and even worse trying to use Grabbing Parry to secure the weapon.

Wrestling will usually be about a point higher than Judo, but since you may have to parry a bunch of times before you get a good grapple,

Brawling is a surprisingly high-percentage option using Knocking a Weapon Away given the skill advantage posed here (and Skill-18 vs Skill-12 is a pretty lopsided contest), but that option is skill vs. skill (even ST-based skill), so the higher the better there.

Of all the options, Kicking with Brawling seems to be the best, especially if you get the chance to set the stage on the Infinite Featureless Plain – you get to Wait, kick-and-retreat, and have optimized your character a bit with Brawling/Kicking-17.

As you start to be less awesome relative to your foe, the odds of a successful disarm go down, and the odds that you’ll get stabbed by his offensive movement (rather than incidentally cut by his armed parries) goes way up. Judo/Karate are the winners here.

However, once you can start working behind your foe, your skill will take it’s toll, as the low-skill opponent can’t absorb the penalties for Wild Swing, and Mack turning to face Marty is his penalized DX vs Marty’s Judo skill – basically unwinnable.

The TG penalties for Grabbing parry make the most cinematically cool move – he stabs, you do a grabbing parry, then arm lock and crush him on your next turn into pretty much an impossible task. What will work is to parry using Judo, then grapple and arm lock as a combination on your own turn. That’s functionally identical but unless your skill is high enough to eat the combination penalties and apply a deceptive attack, odds are you may get cut.

As always: the key here is bracers. Forearm armor that allow you to absorb most, if not all, of the damage from your foe parrying your grapples and strikes with his knife. If you can absorb that damage (and a somewhat common house rule is that such parries do half damage rather than full) you have a much higher chance of getting away unhurt, or at least hurt less.

But it’s a common saying: the winner of a knife fight goes to the hospital; the loser goes to the morgue. GURPS seems to represent that just fine.

3 thoughts on “Melee Academy: Unarmed vs. Knife – Technical Disarms

  1. Hang on, Mack can retreat while in a grapple? What does that look like?

    Why is Marty taking -2 to attack the arm? "Moving past the weapon" may "make this like a strike," but does it actually take hit location penalties like a strike?

    Also, I'm 100% on board with turning down the pain that is Grabbing Parry penalties. To be clear, your option rule is that it defaults to Parry rather than Parry-2. I imagine that, in a cinematic game, you'd accept buying it up to Parry+2 with a Technique, and roll at the higher of base or Grabbing parry so that the bonus can only cancel out penalties?

    Otherwise, looks good. Strap on a pair of boots thick enough to qualify as DR and a damage bonus and go Van Damme. Works for me.

  2. Check out Retreat on p. 23 of TG. You can retreat and get a +1 – it probably looks like dancing.

    You're bypassing the weapon to attack the arm, so the location penalties are doubled – basically -4 like striking the hand or grappling a weapon, or -2 to move past the weapon and capture the arm, which leaves the weapon, hand, and wrist free. That's right there in the text as well, Grabbing the Foe, p. 13.

  3. TheOneRonin here.

    Excellent write-up, Doug! I’m really glad to see that my thread has garnered this much attention. However, I do have some questions and comments about your analysis.

    1. Knife [DX+2]-12; Knife Parry-9
    Not to nitpick, but wouldn’t it be Knife Parry-8? The Basic Set has Large and Small knives at -1 to Parry. I just looked at the weapons table in Martial Arts, and it lists a Long Knife, but that is a 15” – 23” weapon, which sounds a lot bigger than most of us are envisioning. Again, it’s a nitpick, but a -1 to Parry is significant.

    2. Mack will parry, using the knife. He's got Parry-9, and if he does parry, he'll do damage to Marty.
    This is the line of thought I’ve been taking for a while, but it really skips over how the rules handle this.

    BASIC SET PG. 376
    Parrying Unarmed Attacks: If you successfully parry an unarmed attack (bite, punch, etc.) with a weapon, you may injure your attacker. Immediately roll against your skill with the weapon you used to parry. This roll is at -4 if your attacker used Judo or Karate.

    Martial Arts changes this just a little by giving a variable penalty on the attack roll based on what target you are trying to hit (see Aggressive Parry, pg 65).

    So assuming the Knife guy succeeds on his parry, he then has to roll to hit the Judo guy in the Arm at Knife-6 (-4 because the defender used Judo, -2 to target the Arm). That’s less than a 10% chance to do damage. Even if you use just the Basic Set rules, it’s Knife-8, which is only about a 25% to do damage.

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